The present application is related to Japanese Patent Application No. 2000-194215 filed on Jun. 28, 2000.
1. Field of the Invention
The present invention relates to a cam apparatus suitable for application to various automatic machine tools or the like capable of making an output shaft conduct complex movements (a rotational movement and a reciprocal movement in the axial direction thereof) as well as oscillating a housing itself, and to a work shifter using the cam apparatus thereof.
2. Description of the Related Art
Generally, as a work shifter having a work holder which transfers a workpiece to each other between two machines, there is, for example, a tool shifter of a machine tool. This tool shifter takes out a tool held in a tool pot which is accommodated inside a tool rack, and a tool held in a tool pot of a waiting magazine at the side thereof by a transporting arm with an NC order or the like, and subsequently replaces each other and holds the tool in the tool pot. In such a tool shifter, the transporting arm therein may be driven by the cam apparatus.
Incidentally, as such a type of cam apparatus, there is known a cam mechanism where the input shaft and the output shaft are disposed perpendicular to each other in the housing, they are rotatably supported in the housings respectively, as well as the output shaft being further supported in the axial direction thereof to slidably move, and between the input shaft and output shaft is provided a cam mechanism for converting a rotation motion at a constant speed of the input shaft into a normal and reverse rotation motion and a reciprocal motion in the axial direction of the output shaft.
The above cam mechanism is comprised of a roller gear cam fixed to the input shaft, a follower turret spline-engaged to the output shaft and supported rotatably in the housing and also where the cam follower is engaged to the taper rib formed in the outer surface of the above roller gear cam, and an oscillation arm in which the point of support thereof is rotatably supported by the housing, the point of force thereof is engaged with an endless groove cam formed at the one surface of the above roller gear cam, and the point of action thereof is engaged with an annular groove formed at the outer peripheral surface of the output shaft, in which the output shaft reciprocally rotates via the follower turret according to the displacement of the taper rib in the input shaft direction when the input shaft rotates
Incidentally, when the above cam apparatus (pick and place apparatus) is made to drive a transporting arm or the like of the tool shifter, a detaching movement such as inserting or extracting a tool by the transporting arm to a holder by a reciprocal motion in the axial direction of the output shaft, and a moving/waiting movement such as reciprocal moving and waiting of the tool from the tool rack transfer position to the waiting magazine tool holding position by a reciprocal rotation motion or an intermittent rotation motion may be conducted. However, if the tools are held close to each other within the rack to increase accommodation efficiency, in view of interference with adjacent tools when engaging the transportation arm to the tool, it becomes difficult to revolve the transporting arm for engagement.
Therefore, in such a case, it becomes necessary for the transporting arm to have a structure capable of linearly contracting and expanding, and to have a mechanism to operate contraction-expansion therein, and this contraction expansion operating mechanism has to electrically sequentially control the driving apparatus such as an electric motor which is provided separately.
Nevertheless, when the operation of the contraction-expansion operating mechanism in an electric circuit is controlled according to the movement of the above transporting arm, the completion of each action of the transporting arm should be confirmed before operating the driving apparatus of the contraction-expansion operating mechanism, so that the loss time of the operational control becomes large and the electric circuit becomes extremely complex (especially, when it is necessary to overlap the timing of the action, the circuit becomes more complex and setting becomes harder). Thus, there was a problem of increasing the manufacturing cost.
The present invention is made in view of the above matters, and an object is to provide a housing oscillating type cam apparatus which can slide a cam apparatus itself and move the position of an output shaft as approximate to a linear shape as possible, further the sliding motion may be obtained from the rotation of an input shaft of the cam apparatus to slide in synchronous with the action of the output shaft, and to provide a work shifter using the housing oscillating type cam apparatus.
In order to achieve the above object, in a housing oscillating type cam apparatus according to claim 1 of this invention, a cam apparatus comprises: an input shaft rotatably supported in a housing; a first output shaft rotatably supported in the axial direction to slidingly move in the housing; a second output shaft rotatably supported in the housing; a first cam mechanism which transmits the rotation of the input shaft to the rotation movement of the first output shaft; a second cam mechanism which converts the rotation of the input shaft into a reciprocal movement in the axial direction of the first output shaft and transmits it; and a third cam mechanism which converts the rotation of the input shaft into a sliding rotation of the second output shaft and transmits it, wherein the housing oscillating type cam apparatus rotatably supports the housing slidably in a fixed system such as a base, as well as providing a link mechanism in between the second output shaft and the fixed system to convert the sliding rotation of the second output shaft into a sliding movement of the housing.
In the housing oscillating type cam apparatus of the present invention constructed as above, the input shaft not only expands and contracts in the rotational and axial direction according to the rotation of the input shaft, but the whole cam apparatus slides, so that the position on a plane of the first output shaft may be mechanically controlled synchronously with the movement of the first output shaft, without having to provide separately a power source or for control thereof a complex electric circuit, and an operation mechanism or the like, further it may be moved as close to a linear shape as possible.
Further, in the housing oscillating type cam apparatus of the invention according to claim 2, the first output shaft is provided intersecting the input shaft perpendicularly, as well as the second output shaft being provided parallel to the input shaft, whereby the first cam mechanism comprises a roller gear cam fixed to the input shaft and having a taper rib with a predetermined geometrical curve on the outer surface, a follower turret allowing movement in the axial direction of the first output shaft and provided to spline engage to the same shaft on the outer side of the first output shaft as well as being rotatably supported in the housing, and a cam follower provided on the outer surface of the follower turret and engaging in the taper rib of the roller gear cam, the second cam mechanism comprises an endless first groove cam provided at one surface of the roller gear cam and having a predetermined geometrical curve, and a first oscillating arm in which the supporting point rotatably supported in the housing, the point of force is engaged to the first groove cam as well as the point of action being engaged to the groove portion formed at the outer side of the first output shaft, the third cam mechanism comprises an endless second groove cam provided at the other surface of the roller gear cam and having a predetermined geometrical curve, and a second oscillating arm of one end which is fixed to the inner side shaft of the second output shaft and the other end is engaged to the second groove cam, and the link mechanism comprises a third oscillating curve of one end which is fixed to the outer side shaft of the second output shaft and the other end extends in the axial direction, and a connecting bar of which one end is rotatably supported to the extended end of the third oscillating arm and the other end is rotatably supported to the fixed system.
In the housing sliding type cam apparatus of the present invention as structured above, when the input shaft rotates, the first oscillating arm of which the point of force is engaged to the first groove cam of the roller gear cam slides up and down according to the rotation angle, and the oscillation of the first oscillating arm is transmitted to the first output shaft which is slidably supported by a bearing portion of a casing and a follower turret, and the first output shaft reciprocally moves up and down along the axial direction. Further, at the same time, the taper rib of the roller gear cam is displaced in the axial direction of the input shaft according to the rotation angle of the input shaft, and according to this displacement the follower turret which is engaged with a cam follower at the taper rib is rotatingly moved appropriately with the outer shape of the taper rib. Then, the rotation movement of the follower turret is transmitted to the first output shaft which is spline-fitted to the inner side thereof. As a result, the first output shaft reciprocally moves in the axial direction as described above as well as rotatingly moves around the shaft.
On the other hand, the second oscillating arm of which the oscillating end is engaged to the second groove cam of the roller gear cam, is oscillated by the rotation of the input shaft according to the rotation angle thereof, and thereby the second output shaft is oscillatingly rotated, and the oscillation rotation in synchronous with the complex movement of the first output shaft is obtained by the second output shaft. Then, with this oscillating rotation the extended end of the third oscillating arm oscillates, and since the extended end is provided with a connecting bar connecting with the fixed system, take reaction force to the fixed system via the connecting bar, and the housing makes a sliding movement in synchronous with the complex movement of the first output shaft in accordance with the oscillation of the third oscillating arm. Therefore, by the oscillating movement of the housing, the position on a plane of the first output shaft, may be mechanically controlled synchronously with the movement of the first output shaft, without using a complex electric circuit, and may be moved as close as possible to a linear shape. Moreover, the rotation of the input shaft is converted to a rotational/contracting and expanding movement of the first output shaft and an oscillating movement of a housing via a positive cam without saccadic movement such as a roller gear cam or a groove cam. Thus, a housing oscillating type cam apparatus with extremely high movement accuracy and reliability may be obtained.
A work shifter of the present invention according to claim 3, is provided in the center of the two work holder machines, the workpiece held in one of the work holder machines is transported to the other work holder machine, whereby the work shifter comprises a housing oscillating type cam apparatus according to claims 1 or 2, and a work transporting arm fixed to the first output shaft of the housing oscillating type cam apparatus and having a work holder at the tip end portion extending in the radial direction of the first input shaft; wherein the first output shaft revolves the tip end of the work transporting arm and alternately stations towards both the work holder machine sides; the housing oscillating type cam apparatus oscillates and moves towards the tip end direction of the work transporting arm in the stationary period when the work transporting arm is stationary; and the first output shaft extends or contracts and slidably moves during the stationary period of the housing oscillating type cam apparatus.
In the work shifter of the present invention structured as described above, the housing oscillating type cam apparatus may oscillate itself by moving the position of the first output shaft approximate to a linear shape, and also such oscillating motion may be obtained from the rotation of the input shaft of the cam apparatus itself, to be synchronous with the motion of the first output shaft and oscillate. Therefore, a complex construction to sequentially control a transporting arm with a structure that is extendable linearly with a driving device such as an electric motor provided separately does not need to be used, and multiple workpieces held close to the work holder may be engaged with a transporting arm to avoid interference with the adjacent workpiece. Thus, cost reduction of the work shifter may be realized. Further, with the oscillating movement of the housing, the workpiece may be moved more than for the length of the transporting arm, so that even in a case there is a distance between the two work holder machines, work transporting may be conducted coping with the situation. Contrarily, even in a case that the distance is close, the transporting arm may be formed short to conduct the workpiece transporting. Thus, the work shifter may be provided in a narrow space.